Resources
- Peterson , Roger T. and McKenny , Margaret . 1968 . A Field Guide to Wildflowers , Boston : Houghton Mifflin Co. .
- Niering , William A. and Olmstead , Nancy . 1979 . The Audubon Society Field Guide to North American Wildflowers , New York : Alfred A. Knopf . Eastern Region edition and Western Region edition
- Craighead , John J. , Craighead , Frank C. and Davis , Ray J. A Field Guide to Rocky Mountain Wildflowers , Boston : Houghton Mifflin .